This invention relates to a method and apparatus for producing and further processing metallic substances by direct action on liquid metal using centrifugal forces of a rotating induction field, the rotating induction field having initially set the liquid metal in rotation in a rotationally symmetric container wall.
It is known to separate and cool liquid metals in such a way that extremely finely divided metallic powders or wires develop. The cooling rate of the liquid metal determines the structure of the products produced; very high cooling rates even lead to gaseous, i.e., amorphous structures.
Various methods are known for achieving these goals. One of these methods consists of allowing the metal to be atomized or cooled by directing the metal to flow out of a crucible (usually heated and under pressure), through a nozzle provided with a relatively small opening. The metal is then separated and cooled by gas jets or by rapid rotation in usually cooled plates, hollow spherical vessels, cylinders, etc. A combination of these methods has also been proposed.
Other methods provide for metals to be rapidly cooled by introducing them into a liquid which is forced at right angles onto a container wall by centrifugal forces.
However, these known methods have the disadvantage that rapidly rotating components are required, which at these high speeds, lead to unbalance and contamination problems.
The above discussed problems do not exist in the method disclosed by FR-A-2,391,799. In that method, the rotational motion of the liquid metal is brought about inductively and so movable parts are not required. Nevertheless, this known method has a disadvantage in that the liquid metal is rotated in a pipe which is closed at the bottom except for a small central opening nozzle through which the metal must also leave the pipe. This small nozzle presents two important problems. First, the output from the nozzle is limited; and second, this nozzle represents a blockage risk and is subjected to rapid abrasion wear. In addition, as a result of the centrifugal force, the liquid metal is thrust in a tubular form onto the inner wall of the pipe during the rotational motion and therefore has hardly any chance to escape through the axially arranged nozzle.